The viewable contents of a computer file, such as a text document, spreadsheet, digital photograph, Web page, or other image rendered on a conventional display screen, may possess a size exceeding the viewable boundaries of the display screen. To address this issue, an individual may utilize a scrolling method to scroll the image relative to the display screen. Scrolling, as used herein and as is known in the art, describes the movement of an image relative to a display screen in a particular direction. For example, “scrolling down” generally describes moving the viewable contents of a file (such as a text document or image) relative to a display screen so as to produce an effect of moving down in the document or image. Similarly, the terms scroll up, scroll left and scroll right relate to moving the viewable contents of a file relative to a screen so as to produce an effect of moving a document or image up, left, and right, respectively. The term scrolling as used herein also includes panning, which is the automatic and/or continuous scrolling of an image, often in response to a single command or input.
Scroll wheels have been provided on computer mice, and have been used by computer operators to move an image on a display screen. A scroll wheel assembly typically includes a rotatable scroll wheel and a sensor to measure and encode rotation. Typically, the scroll wheel is located within a housing of a mouse or other peripheral computer device. A portion of the scroll wheel protrudes upwardly out of an opening in the housing, and is rotated in order to vertically scroll the image displayed on the screen. An example of a mouse including a known scroll wheel assembly is described in U.S. Pat. No. 5,912,661, entitled “Z-ENCODER MECHANISM” which is hereby fully incorporated by reference.
In operation, a conventional scroll wheel is normally rotated about a transversely extending axis secured within a housing. An encoder wheel is coupled to the scroll wheel and rotates when the scroll wheel rotates. As the scroll wheel is rotated, an encoder senses the rotation of the encoder wheel, and delivers a corresponding signal to a host computer. That signal can be used to move an image, as is known in the art and disclosed in U.S. Pat. No. 5,912,661. Notably, this allows a user to scroll the image without changing the position of the mouse and/or the cursor, and instead only requires rotating the scroll wheel (versus the entire mouse or other device) with a thumb or finger. However, displayable portions of spreadsheets and many other types of documents and screen images are often wider than the display screen, and the user must also scroll horizontally across the screen to see the entire file. When the user needs to move the image horizontally across the display screen, the user must typically perform additional steps beyond what is required for vertical scrolling. This can include locating a graphical user interface in the form of a horizontal scroll bar (usually located near the bottom of the display), positioning the cursor on the scroll bar, and then rotating the wheel. Locating the scroll bar can be very difficult for people with bad eyesight, small display screens and/or poor hand-eye coordination. Using a horizontal scroll bar also requires a user to shift his or her gaze from the portion of the document being viewed, and then relocate that portion after horizontal scrolling. Even if the size of the horizontal scroll bar and/or the screen resolution can be adjusted, the user must nevertheless perform additional pointing tasks which are more time-consuming and mentally intensive than simply rotating a wheel or pushing a button. Alternative graphically assisted tools for horizontal scrolling (e.g., positioning a cursor over a horizontal scroll bar, selecting the scroll bar, and moving the cursor) also require cursor repositioning, and have similar drawbacks.
Microside Corporation of Miami, Fla. offers a “Micro Scroll II” mouse that permits a user to scroll an image in multiple perpendicular directions. This mouse includes a first rotatable wheel for scrolling an image up and down, and a second, separate rotatable wheel for scrolling an image left and right. The rotatable wheels are oriented so they extend and rotate in planes that are perpendicular to each other. The two scroll wheels are independently operable. However, this arrangement has drawbacks. The two wheels take up limited space on the upper surface area on the mouse, which could be used for supporting the hand of the user or for additional input keys. Further, the two wheels are relatively small in size so as to accommodate both wheels on the upper surface of the mouse. The smaller sized scroll wheels make the scrolling more difficult to control. Additionally, the location of the horizontal scroll wheel can be inconvenient for effective control. Further, with this design, it might be difficult for some users to easily reach and manipulate both of the wheels.
Accordingly, there remains a need for improved input devices facilitating scrolling in multiple directions.